1. Field of the Invention
The invention pertains to the field of variable compression actuator systems. More particularly, the invention pertains to a control method for a variable compression actuator system.
2. Description of Related Art
Prior art FIGS. 1 and 2 show an adjustment device for a variable compression ratio engine as disclosed in WO 2005/098219. The engine block 100 has as at least one cylinder in which a piston 2 moves by means of a transmission device 1.
The transmission device 1 has a transmission member 3 integral with piston 2 and cooperating on one side with a rolling guide device 4 and a sprocket wheel 5 on the other side. The sprocket wheel 5 is connected to a connecting rod 6 jointed to crankshaft 9 to determine the transmission of movement between the piston 2 and the crankshaft 9.
The sprocket wheel 5 cooperates on the opposite side of the transmission member 3 with a control rack 7. The vertical position of the control rack 7 in relation to the engine block 100 is guided by a control device 12. The control device has a control jack 8 of which its jack piston 13 is guided into a jack cylinder 112 set into the engine block 100. The jack cylinder 112 is bored or fitted into the engine block 100. The jack cylinder 112 is secured in an upper part by a jack head 113 that is screwed into the engine block 100.
The sprocket wheel 5 has a first set of serrations 52 for engaging the serrations 74 of the control rack 7 and a second set of teeth 51 on an opposite side of the sprocket wheel 5 for engaging a first rack of the transmission member 3 with corresponding teeth. Opposite the first rack of the transmission member 3 is another rack 37 with teeth that cooperate with a roller 40 of a rolling guide device 4 integral with the engine block 100. The engine block 100 on the side of a cylinder 110 has a support 41 with racks 46 allowing synchronization of the displacement of the roller 40 with the piston 2.
The jack piston 13 divides a chamber formed between the jack head 113 and control rack 7 in which the control device 12 is received into an upper chamber 121 and a lower chamber 122. Movement of the jack piston 13 is further controlled by a control rod 20 which is received within a bore of the jack piston 13 along with the lower jack rod 16. The control rod 20 limits the movement of the jack piston 13 between two springs 22 and loaded stops 130. The limited movement of the control rod 20, and thus the jack piston 13 is sufficient to allow the jack piston 13 to pivot slightly, so that the control rack 7 may position itself with in the engine block 100 and align the teeth 74 of the rack 7 with the teeth 52 of the sprocket wheel 5.
The adjustment of the engine's effective compression ratio is achieved by modifying the original position of the stroke of the piston 2 in relation to the cylinder 110 by sprocket wheel 5, mounted freely at the top end of a connection rod 6, a transmission member 3, integral with the piston 13 and a control rack 7, in which the position is regulated by the control device 12.
The present invention provides an alternate control system for the adjustment device disclosed in WO 2005/098219,, which provides a quicker response.